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Research Project: Improving the Quality of Grapes, Other Fruits, and their Products through Agricultural Management


2015 Annual Report

Objective 1: Identify, develop, and define analysis techniques to evaluate primary and secondary metabolites of fruit, fruit products, and wine. [NP 305; C1, PS1B] Sub-objective 1.A. Determine quality indicator metabolites and analytical methods for their analysis; evaluate and optimize new methods where insufficient data exists. Sub-objective 1.B. Deploy quality component measurements to optimize agricultural practices targeted at improving product quality. Objective 2: Integrate canopy- and fruit-specific management practices in grapes and berries to enhance crop productivity and fruit quality. [NP 305; C1, PS1B] Sub-objective 2.A. Determine development of fruit quality parameters as driven by the interaction between temperature and the timing of temperature anomalies during critical periods of fruit development. Sub-objective 2.B. Quantify standard industry pruning methods for grapevines and develop formal pruning standards necessary to achieve targeted goals for canopy structure; evaluate efficacy of manual pruning and algorithm-driven mechanical systems to achieve canopy structure goals. Sub-objective 2.C. Define canopy and fruit temperature thresholds leading to reduced fruit marketability in drip-irrigated blueberry fields. Objective 3: Develop cultural management strategies that mitigate the impact of abiotic stresses (drought and cold) in winegrapes. [NP 305; C1, PS1B] Sub-objective 3.A. Determine how irrigation spatial delivery, frequency, and amount affect the photosynthesis, water use efficiency, crop load and berry maturity of winegrapes. Sub-objective 3.B. Determine the influence of seasonal water deficit on cold acclimation during bud dormancy in winegrapes.

Project objectives will be accomplished by integrating research across three core disciplines: food chemistry- phytochemical analysis, plant-microclimate interactions, and crop physiology. A systematic approach in targeted fruit quality compound analysis to predict the magnitude by which climate and cultural factors impact fruit quality components will be used. This approach will allow us to improve and define analytical methods for plant metabolite analysis that advance our comprehension of the relationships among canopy management, canopy microclimate, water management, and vine cold hardiness and their effects on fruit development, fruit quality components, and vine physiology. If weather interferes with experimental treatments and sampling, experiments will be adjusted and extended an additional growing season.

Progress Report
During the past year, we have continued to research how agricultural management practices improve fruit and fruit product quality. We continue to explore the relationships between genotypes, agricultural practices (i.e., fertigation) and biotic stresses (i.e., vine virus status) affecting fruit primary and secondary metabolites (i.e., sugars, organic acids, anthocyanins, proanthocyanidins). We published a review article detailing methods for distinguishing among two commonly misidentified Rubus species, R. coreanus (Korean black raspberry) and R. occidentalis L. (American black raspberry). We evaluated sample preparation and metabolite analysis methods and used selected methods to demonstrate detection of species adulteration in R. coreanus and R. occidentalis L. by pigment (anthocyanin) products. Efforts were also made to correct the misconception that blackberry and raspberry (both within genus Rubus) fruits are high in sorbitol (sugar alcohols). As part of our project objective to investigate the relationship between sequential growing seasons of deficit irrigation and severity and duration of drought stress on subsequent bud cold hardiness and productivity in winegrape, we completed another year of irrigation treatment applications and data collection. During winter dormancy, we used differential thermal analysis to quantify dormant bud cold hardiness in one year old canes sampled from irrigation field trial plots that had been deficit irrigated with 70 or 35% of estimated vine water demand for at least six sequential growing seasons. In the spring, we rated cold injury severity and vine productivity of nineteen winegrape cultivars from these irrigation trial plots. To develop an index for monitoring vine water status, we validated the efficiency of a neural network model to predict well-watered vine canopy temperature for a third season by monitoring the canopy temperature of well-watered and deficit-irrigated vines in irrigation trial plots of the winegrape cultivars Malbec and Syrah. Plots were supplied weekly or three times per week with differing percentages of estimated vine water demand and data were collected to determine how irrigation amount and event frequency affect water productivity, crop load and berry composition at fruit maturity. We also evaluated the neural network model for predicting well-watered canopy temperature in other winegrape cultivars by monitoring the canopy temperature of the winegrape cultivars Cabernet Franc and Chardonnay in field trial plots that were irrigated to supply 70 or 35% of estimated vine water demand.

1. Species adulteration in food. Consumers are concerned about accurate labeling of food for health, safety and economic reasons. Most Korean growers and researchers of Rubus coreanus are in fact working with R. occidentalis L. (American black raspberries). ARS scientists in Parma, Idaho, Corvallis, Oregon, and a Canadian collaborator, summarized fruit, plant, and phytochemical characteristics that distinguish the two species. This effort will aid in plant species identification, fruit recognition, and determining product adulteration (accidental or otherwise) in the International marketplace.

2. Rubus fruit misconceptions. It is unclear how the misconception that blackberry and raspberry fruits contain significant amounts of sorbitol (sugar alcohols) began. High levels of sugar alcohol consumption might lead to digestive issues for some. An ARS scientist in Parma, Idaho, compiled the Rubus fruit sugar alcohol concentrations reported in the literature and demonstrated Rubus fruits are very low in sugar alcohols. This information provides consumers with accurate information about sorbitol in Rubus, increases the variety of goods available to sorbitol-sensitive individuals, and increases product demand.

3. Bokbunja product adulterated. Native Korean black raspberry, known as bokbunja (Rubus coreanus Miquel), foods and supplement products are increasing in popularity in South Korea and the U.S. Though, much of the information and research findings from bokbunja are confusing due to inaccurate representations, and studies being based on incorrect species identifications. An ARS scientist in Parma, Idaho, used anthocyanin profiles to detect species adulteration in bokbunja products available in the International marketplace. The majority of samples analyzed were actually made from R. occidentalis L., not R. coreanus. This research will aid bokbunja growers, processors, and researchers in reporting the correct Rubus species to prevent adulteration and confusion in the scientific literature.

Review Publications
Lee, J. 2015. Analysis of bokbunja products show they contain Rubus occidentalis L. fruit. Journal of Functional Foods. 12:144-149.
Lee, J., Dossett, M., Finn, C.E. 2014. Mistaken identity: clarification of Rubus coreanus Miquel (bokbunja). Molecules. 19:10524-10533.
Lee, J. 2015. Sorbitol, Rubus fruit, and misconception. Food Chemistry. 166:616-622.
Finn, C.E., Strik, B.C., Yorgey, B.M., Peterson, M.E., Lee, J., Martin, R.R., Hall, H.K. 2014. ‘Columbia Star’ thornless trailing blackberry. HortScience. 49(8):1108–1112.
Bushakra, J., Bryant, D.W., Dossett, M., Vining, K.J., Vanburen, R., Gilmore, B.S., Lee, J., Mockler, T.C., Finn, C.E., Bassil, N.V. 2015. A genetic linkage map of black raspberry (Rubus occidentalis) and the mapping of Ag4 conferring resistance to the aphid Amphorophora agathonica. Theoretical and Applied Genetics. 128:1631-1646.
Schreiner, R.P., Scagel, C.F., Lee, J. 2014. N, P, and K supply to Pinot noir grapevines: Impact on berry phenolics and free amino acids. American Journal of Enology and Viticulture. 65:43-49.
Bassil, N.V., Dossett, M., Hummer, K.E., Mockler, T., Filichkin, S., Peterson, M.E., Lee, J., Fernandez, G., Perkins-Veazie, P., Weber, C., Agunga, R., Rhodes, E., Scheerens, J.C., Lewers, K.S., Graham, J., Fernandez Fernandez, F., Yun, S.J., Finn, C.E. 2014. Genetic and developing genomic resources in black raspberry. Acta Horticulturae. 1048:19-24.
Tarara, J.M., Chaves, B., Sanchez, L., Dokoozlian, N. 2014. Cordon wire tension can be used for static and dynamic prediction of grapevine yield. American Journal of Enology and Viticulture. 65:443-452.
Dami, I.E., Li, S., Bowen, P.A., Bogdanoff, C.P., Shellie, K., Willwerth, J. 2015. Foliar applied abscisic acid increases 'Chardonnay' grapevines (Vitis vinifera) bud freezing tolerance during Autumn cold acclimation. HortTechnology. 25:293-305.
Shellie, K. 2015. Foliar reflective film and water deficit increase anthocyanin to soluble solids ratio during ripening in Merlot. American Journal of Enology and Viticulture. 66:348-356.